This invention relates to an actuator structure of a suspension apparatus for a vehicle.
Heretofore, to vary the alignment in a suspension apparatus for a vehicle such as a caster angle, a camber angle, and a toe-in angle, there has been known an alignment apparatus comprising an actuator mounted on a suspension arm or the like for varying the arm length and the mounting position of the suspension arm on the vehicle body, and a controller or the like for controlling the actuator.
With such an arrangement, when the controller drives the actuator, relative positions of the arm, strut, and the like constructing the suspension apparatus are varied, and the alignment is varied.
For example, in general, when the vehicle is turning, since the vehicle body tends to roll, the ground camber angle of the outer wheel in relation to the turning direction increases in the positive direction and the ground camber angle of the inner wheel in relation to the turning direction increases in the negative direction. In such a case, in a vehicle provided with the above alignment apparatus, the controller detects turning of the vehicle to control the actuator, the ground camber angle of the outer wheel increasing in the positive direction and the ground camber angle of the inner wheel increasing in the negative direction are decreased to improve contact of the individual wheels with the ground, thereby improving the turning stability and the turning limit of the vehicle. Further, when the vehicle is running straight, the caster angle and the like is controlled to improve the straight running stability of the vehicle.
As an actuator in such an alignment apparatus, there has been known, for example, one of which is shown in FIG. 6, wherein a hydraulic cylinder 05 of a suspension arm 04 is disposed between a knuckle 02, for rotatably supporting a rear wheel 01, and a sub-frame 03 of a vehicle body.
However, in the above prior art actuator for alignment control, since the actuator is disposed in the intermediate portion of the suspension arm 04, due to movement of the suspension, the actuator is applied with a high load in directions other than the expansion/contraction direction of the actuator or generates a resonance phenomenon, and the actuator is required to have a high durability and tends to be large in size.
Further, since the length of the suspension arms 04 is controlled, a curvature differs between a expanded condition and a contracted condition, and thus a geometrical change due to suspension stroke is not constant.